Development of chromed dyes on nylon by steaming under pressure



Patented May 27, 1947 DEVELOPMENT CHROMED DYES ON NYLON BY STEAMING UNDER PRES- SURE Thomas Skeuse, Jr., Bayside, N. Y., assignor to Geigy Company, Inc., New York, N. Y... a corporation of New "York No Drawing. Application June 11, 1945, Serial No. 598,897

2 Claims.

- i This invention relates to a method of dyeing synthetic linear polyamide fibres, e. g. nylon. Such fibres have been dyed heretofore with acetate colors and other dyestuffs but as far as fastness to light and washing is concerned, these dyeings left much to be desired. My method fills a need in the dyeing of these important new textile fibres.

This'method particularly relates to an improved process for the application of chrome colors which, when developed with chrome on polyamide fibres, produce shades of unexcelled fastness.

Prior to my invention, the use of chrome colors has been suggested for the dyeing of polyamide fibres but results have been far from satisfactory-not only from the standpoint of insufiicient fastness but also because it has not been possible to arrive at the proper development of the ma-- jority of chrome colors. Uneven dyeing and inconsistent results have been caused by faulty development when applying chrome colors to polyamide fibre in all previous methods.

Recognition must be given to the fact that chrome colors do not produce the ultimate in fixation unless full development is obtained and consequently will not produce shades which will resist severe washing. Therefore, my invention serves the double purpose of not only producing uniform and consistent resultsbut also shades which possess fastness to extremely severe soaping which cannot be approached with ordinary methods.

I have discovered that full development and fixing of chrome colors on polyamide fibres may be obtained bysteaming at a pressure well above atmospheric pressure in the presence of an excess of a soluble chromate.

My new method of dyeing is based on this discovery. It may be carried. out by the following steps:

(1) The first step consists in dyeing the nylon fibre by boiling it in an acid bath containing a chrome color and an acid, such as acetic acid or formic acid or sulphuric acid. If necessary, the

bath is exhausted by a further addition of acid.

The fibre may be in the form of yarn or piece goods or knit goods. This step does not differ from the first step of the usual method of applying chrome colors to other fibres.

(2) The second step consists in immersing the dyed nylon fibre in a fresh warm acid bath con.

taming a soluble chromium salt, such as bichromate of soda or bichromate of potash, in a concentration of about one-half per cent. by volume. This is many times greater than the concentration of chromium salt used in the usual method of treating other fibres. It places on the nylon fibre an amount of chromium salt in excess of the amount theoretically required to react with the dye on the fibre. After about ten minutes in this bath, the fibre is extracted lightly but not rinsed. (3) The third step consists in steaming the dyed and chromated fibre at a pressure at or above eight pounds above atmospheric pressure at a temperature of 235 F. or above. The steaming is continued for about forty-five minutes.

(4) The fourth step consists in soaping and rinsing the fibres after which they may be dried. The result of the process is fully todevelop the color and to make it fast to a hot soap test.

The following specific examples illustrate the use of my method:

EXAMPLE I First step Amount per lbs.

of fibre, pounds Prepare bath containing:

Erio Chrome Flavine A. (Color Index Acetic acid 56% solution 1.5 Water sufiicient to immerse fibre. Enter material at F. Raise to boil in 45 minutes. Boil for 45 minutes. Cool.

Add acetic acid, 56% solution 0.75

Raise to boil. Boil 15 minutes. Rinse,

Second step Enter material at F. Run at 160 F. for 1 10 minutes. Extract lightly. No rinse.

Third step Steam at 8 lbs. pressure for 45 minutes.

' Fourth step Soap material at F. for 10 minutes. 2 warm rinses; 1 cold rinse. Extract and dry.

Exmm: 11

First step Amount per 100 lbs. of fibre. pounds Prepare bath containing:

Eric Chrome Red B (Color Index No.

Water to make 100%.

. Enter material at 160 F. Run at 160 F. for

10 minutes. Extract lightly. No rinse.

Third step Steam at 8 lbs. pressure for 45 minutes.

Fourth step Soap material at 180 F. for 10 minutes. 2 warm rinses; 1 cold rinse. Extract and dry.

Chrome colors" as used in this specification Number mean soluble dyes capable of reacting with soluble chromium salts to form insoluble lakes.

What I claim is:

1. The method of dyeing synthetic linear polyamide fibres, which comprises boiling the fibre in an acid bath containing a chrome color, immersing the fibre in an acid bath containing a soluble chromium salt in a concentration of about one-halt per cent. by volume, and then steamin the fibre at a super-atmospheric pressure of at least approximately eight pounds.

2. The method of developing and fixing chrome colors on synthetic linear polyamide fibres, which comprises steaming the dyed fibre at a superatmospheric pressure of at least approximately eight pounds in the presence of an excess of soluble chromate.

I'HOMAS SKEUSE, JR.

REFERENCES CITED The following references are of record in the file of this patent:

FQREIGN PATENTS Country Date Italy Feb. 15, 1940 OTHER REFERENCES Textile Colorist, vol. 62, No. 742, page 696,. 

